Non-invasive Brain Stimulation for Alcohol Use Disorders: State of the Art and Future Directions

Stimulation Effects Mapping for Optimizing Coil Placement for Transcranial Magnetic Stimulation

The position and orientation of transcranial magnetic stimulation (TMS) coil, which we collectively refer to as coil placement, significantly affect both the assessment and modulation of cortical excitability. TMS electric field (E-field) simulation can be used to identify optimal coil placement. However, the present E-field simulation required a laborious segmentation and meshing procedure to determine optimal coil placement. We intended to create a framework that would enable us to offer optimal coil placement without requiring the segmentation and meshing procedure. We constructed the stimulation effects map (SEM) framework using the CASIA dataset for optimal coil placement. We used leave-one-subject-out cross-validation to evaluate the consistency of the optimal coil placement and the target regions determined by SEM for the 74 target ROIs in MRI data from the CASIA, HCP15 and HCP100 datasets. Additionally, we contrasted the E-norms determined by optimal coil placements using SEM and auxiliary dipole method (ADM) based on the DP and CASIA II datasets. We provided optimal coil placement in 'head-anatomy-based' (HAC) polar coordinates and MNI coordinates for the target region. The results also demonstrated the consistency of the SEM framework for the 74 target ROIs. The normal E-field determined by SEM was more significant than the value received by ADM. We created the SEM framework using the CASIA database to determine optimal coil placement without segmentation or meshing. We provided optimal coil placement in HAC and MNI coordinates for the target region. The validation of several target ROIs from various datasets demonstrated the consistency of the SEM approach. By streamlining the process of finding optimal coil placement, we intended to make TMS assessment and therapy more convenient.

Modulation of Alcohol Use Disorder by Brain Stimulation

Currently available therapeutic modalities for alcohol use disorder (AUD) produce limited effect sizes or long-term compliance. Recent methods that were developed to modulate brain activity represent potential novel treatment options. Various methods of brain stimulation, when applied repeatedly, can induce long-term neurobiological, behavioral, and cognitive modifications. Recent studies in alcoholic subjects indicate the potential of brain stimulation methods to reduce alcohol craving, consumption, and relapse. Specifically, deep brain stimulation (DBS) of the nucleus accumbens or non-surgical stimulation of the dorsolateral prefrontal cortex (PFC) or medial PFC and anterior cingulate cortex using transcranial magnetic stimulation (TMS) has shown clinical benefit. However, further preclinical and clinical research is needed to establish understanding of mechanisms and the treatment protocols of brain stimulation for AUD. While efforts to design comparable apparatus in rodents continue, preclinical studies can be used to examine targets for DBS protocols, or to administer temporal patterns of pulsus similar to those used for TMS, to more superficial targets through implanted electrodes. The clinical field will benefit from studies with larger sample sizes, higher numbers of stimulation sessions, maintenance sessions, and long follow-up periods. The effect of symptoms provocation before and during stimulation should be further studied. Larger studies may have the power to explore predictive factors for the clinical outcome and thereby to optimize patient selection and eventually even develop personalization of the stimulation parameters.

What makes a medical intervention invasive?

The classification of medical interventions as either invasive or non-invasive is commonly regarded to be morally important. On the most commonly endorsed account of invasiveness, a medical intervention is invasive if and only if it involves either breaking the skin ('incision') or inserting an object into the body ('insertion'). Building on recent discussions of the concept of invasiveness, we show that this standard account fails to capture three aspects of existing usage of the concept of invasiveness in relation to medical interventions-namely, (1) usage implying that invasiveness comes in degrees, (2) that the invasiveness of an intervention can depend on the characteristics of the salient alternative interventions, and (3) that medical interventions can be invasive in non-physical ways. We then offer the beginnings of a revised account that, we argue, is able to capture a wider range of existing usage. Central to our account is a distinction between two properties: basic invasiveness and threshold invasiveness We end by assessing what the standard account gets right, and what more needs to be done to complete our schematic account.

Electric Field Modeling in Personalizing Transcranial Magnetic Stimulation Interventions

The modeling of transcranial magnetic stimulation (TMS)-induced electric fields (E-fields) is a versatile technique for evaluating and refining brain targeting and dosing strategies, while also providing insights into dose-response relationships in the brain. This review outlines the methodologies employed to derive E-field estimations, covering TMS physics, modeling assumptions, and aspects of subject-specific head tissue and coil modeling. We also summarize various numerical methods for solving the E-field and their suitability for various applications. Modeling methodologies have been optimized to efficiently execute numerous TMS simulations across diverse scalp coil configurations, facilitating the identification of optimal setups or rapid cortical E-field visualization for specific brain targets. These brain targets are extrapolated from neurophysiological measurements and neuroimaging, enabling precise and individualized E-field dosing in experimental and clinical applications. This necessitates the quantification of E-field estimates using metrics that enable the comparison of brain target engagement, functional localization, and TMS intensity adjustments across subjects. The integration of E-field modeling with empirical data has the potential to uncover pivotal insights into the aspects of E-fields responsible for stimulating and modulating brain function and states, enhancing behavioral task performance, and impacting the clinical outcomes of personalized TMS interventions.

A pilot, randomized clinical trial: Left dorsolateral prefrontal cortex intermittent theta burst stimulation improves treatment outcomes in veterans with alcohol use disorder

BACKGROUND

Transcranial magnetic stimulation (TMS) offers a promising treatment avenue to modulate brain function in alcohol use disorder (AUD). To the best of our knowledge, this pilot study is the first randomized, double-blind, sham-controlled trial to deliver intermittent theta burst stimulation to the left dorsolateral prefrontal cortex (DLPFC) among US veterans with AUD. We hypothesized that 20 sessions of real TMS are tolerable and feasible. As a secondary line of inquiry, we hypothesized that, relative to sham TMS, individuals receiving real TMS would experience greater reductions in 6-month relapse rates, anhedonia, and alcohol cue-reactivity.

METHODS

Veterans (n = 17, one woman) were enrolled in a double-blind, sham-controlled trial (2-3 sessions/day; 7-10 days; 600 pulses/session; 20 sessions). Pre- and posttreatment assessments included responses to self-report questionnaires and functional magnetic resonance imaging measures of alcohol cue-reactivity. Alcohol consumption was assessed for 6 months. Linear mixed-effects models were constructed to predict posttreatment craving, mood, and cue-reactivity.

RESULTS

Individuals who received active iTBS (n = 8) were less likely to relapse within 3 months after treatment than the sham-treated group (n = 9) (OR = 12.0). Greater reductions in anhedonia were observed following active iTBS (Cohen's d = -0.59), relative to sham (d = -0.25). Alcohol cue-reactivity was reduced following active iTBS and increased following sham within the left insula (d = -0.19 vs. 0.51), left thalamus (d = -0.28 vs. 0.77), right insula (d = 0.18 vs. 0.52), and right thalamus (d = -0.06 vs. 0.62).

CONCLUSIONS

Relative to sham, we demonstrate that 20 sessions of real left DLPFC iTBS reduced the likelihood of relapse for at least 3 months. The potential utility of this approach is underscored by observed decreases in anhedonia and alcohol cue-reactivity-strong predictors of relapse among veterans. These initial data offer a valuable set of effect sizes to inform future clinical trials in this patient population.

Medial Prefrontal Cortex Theta Burst Stimulation Improves Treatment Outcomes in Alcohol Use Disorder: A Double-Blind, Sham-Controlled Neuroimaging Study

Background

Alcohol use disorder (AUD) is associated with elevated brain response to cues. Recent studies have suggested that theta burst stimulation (TBS) to the medial prefrontal cortex (MPFC) can decrease reactivity to cues in a transdiagnostic manner. The goal of this clinical trial was to evaluate the effect of continuous TBS as a tool to decrease drinking behavior and brain reactivity to alcohol cues among individuals with AUD.

Methods

A total of 50 individuals with AUD were recruited from an intensive outpatient treatment program. Using a randomized, double-blind, sham-controlled design, participants received 10 sessions of continuous TBS (left frontal pole, 1 session/10 days, 110% resting motor threshold, 3600 pulse/session, cue provocation before and during session). Brain reactivity to alcohol cues was acquired at four time points: at baseline and after all TBS sessions (1 month, 2 months, and 3 months).

Results

Overall, 80% of the participants completed all TBS sessions. Individuals who received real TBS were 2.71 times more likely to remain enrolled in the study after 3 months and 3.09 times more likely to remain sober 3 months after treatment initiation. Real TBS also led to a significantly greater reduction in brain reactivity to alcohol cues, specifically a reduction in MPFC-striatum and MPFC-insula connectivity 2 and 3 months after TBS treatment.

Conclusions

Ten days of MPFC TBS is well tolerated, reduces drinking, and decreases brain reactivity to alcohol cues for up to 3 months after treatment initiation. These results pave a critical next step in the path toward developing transcranial magnetic stimulation as an intervention for AUD and disorders associated with elevated cue reactivity.

Evaluating Craving in Alcohol Use Disorder: Psychometric Characteristics of the Craving Typology Questionnaire-15 (CTQ-15)

AIMS

The Craving Typology Questionnaire (CTQ) is a psychometric instrument used to assess alcohol craving in normal controls and subjects with alcohol use disorder (AUD). It allows a dimensional self-rating assessment of craving according to a three-pathway psychobiological model of craving distinguishing craving into a reward, relief and obsessive component. The aim of the present study is to evaluate psychometric properties of the CTQ-15, a revised version of CTQ with 15 items.

METHODS

The CTQ-15 was firstly administered to two groups of control subjects, one (414 subjects) used for the exploratory factor analysis and the other one (415 subjects) for the confirmatory factor analysis. A three-factor model was assessed and compared to alternative models.

RESULTS

The resulting structure was in line with the original scale CTQ. Obsessive craving accounted for 15.20% of the total variance, relief craving for the 13.99% and reward craving for 13.13% of the total variance. The three-factor model (M1) reached good fit indices (CFI = 0.96, TLI = 0.95, RMSEA = 0.06 and SRMR = 0.05) and was significantly better than other alternative models. Reliability showed good internal consistency for each scale, i.e. obsessive craving (α = 0.92), relief craving (α = 0.82) and reward craving (α = 0.81).

CONCLUSIONS

The CTQ-15 proved to be reliable and practical for identifying the three dimensions of craving in clinical practice. Craving plays a crucial role in the mechanisms of dependence and relapse; thus, characterizing the craving can be fundamental to a targeted drug therapy.

The neurobiological markers of acute alcohol's subjective effects in humans

The ingestion of alcohol yields acute biphasic subjective effects: stimulation before sedation. Despite their predictive relevance to the development of alcohol use disorders (AUD), the neurobiological markers accounting for the biphasic effects of alcohol remain poorly understood in humans. Informed by converging lines of evidence, this study tested the hypothesis that alcohol ingestion acutely increases gamma-aminobutyric acid (GABA)-mediated inhibition, which would positively and negatively predict the feeling of stimulation and sedation, respectively. To do so, healthy participants (n = 20) ingested a single dose of 94% ABV alcohol (males: 1.0 ml/kg; females: 0.85 ml/kg) in a randomized placebo-controlled cross-over design. The alcohol's biphasic effects were assessed with the Brief-Biphasic Alcohol Effects Scale, and non-invasive neurobiological markers were measured with transcranial magnetic stimulation, before and every 30 min (up to 120 min) after the complete ingestion of the beverage. Results showed that acute alcohol ingestion selectively increased the duration of the cortical silent period (CSP) as compared to placebo, suggesting that alcohol increases non-specific GABAergic inhibition. Importantly, CSP duration positively and negatively predicted increases in the feeling of stimulation and sedation, respectively, suggesting that stimulation emerges as GABAergic inhibition increases and that sedation emerges as GABAergic inhibition returns to baseline values. Overall, these results suggest that modulations of GABAergic inhibition are central to the acute biphasic subjective effects of alcohol, providing a potential preventive target to curb the progression of at-risk individuals to AUD.

Targeting prefrontal cortex GABAergic microcircuits for the treatment of alcohol use disorder

Developing novel treatments for alcohol use disorders (AUDs) is of paramount importance for improving patient outcomes and alleviating the suffering related to the disease. A better understanding of the molecular and neurocircuit mechanisms through which alcohol alters brain function will be instrumental in the rational development of new efficacious treatments. Clinical studies have consistently associated the prefrontal cortex (PFC) function with symptoms of AUDs. Population-level analyses have linked the PFC structure and function with heavy drinking and/or AUD diagnosis. Thus, targeting specific PFC cell types and neural circuits holds promise for the development of new treatments. Here, we overview the tremendous diversity in the form and function of inhibitory neuron subtypes within PFC and describe their therapeutic potential. We then summarize AUD population genetics studies, clinical neurophysiology findings, and translational neuroscience discoveries. This study collectively suggests that changes in fast transmission through PFC inhibitory microcircuits are a central component of the neurobiological effects of ethanol and the core symptoms of AUDs. Finally, we submit that there is a significant and timely need to examine sex as a biological variable and human postmortem brain tissue to maximize the efforts in translating findings to new clinical treatments.

Compulsive alcohol drinking in rodents is associated with altered representations of behavioral control and seeking in dorsal medial prefrontal cortex

A key feature of compulsive alcohol drinking is continuing to drink despite negative consequences. To examine the changes in neural activity that underlie this behavior, compulsive alcohol drinking was assessed in a validated rodent model of heritable risk for excessive drinking (alcohol preferring (P) rats). Neural activity was measured in dorsal medial prefrontal cortex (dmPFC-a brain region involved in maladaptive decision-making) and assessed via change point analyses and novel principal component analyses. Neural population representations of specific decision-making variables were measured to determine how they were altered in animals that drink alcohol compulsively. Compulsive animals showed weakened representations of behavioral control signals, but strengthened representations of alcohol seeking-related signals. Finally, chemogenetic-based excitation of dmPFC prevented escalation of compulsive alcohol drinking. Collectively, these data indicate that compulsive alcohol drinking in rats is associated with alterations in dmPFC neural activity that underlie diminished behavioral control and enhanced seeking.

How Should Transcranial Direct Current Stimulation be Used in Populations With Severe Alcohol Use Disorder? A Clinically Oriented Systematic Review

Background and rationale. Severe alcohol use disorder (SAUD) is a major public health concern, given its massive individual, interpersonal, and societal consequences. The available prevention and treatment programs have proven limited effectiveness, as relapse rates are still high in this clinical population. Developing effective interventions reducing the appearance and persistence of SAUD thus constitutes an experimental and clinical priority. Among the new therapeutic approaches, there is a growing interest for noninvasive neuromodulation techniques, and particularly for transcranial direct current stimulation (tDCS) as an adjunctive treatment in neuropsychiatric disorders, including SAUD. Methods. We propose a systematic review, based on preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines, evaluating the available evidence on the effectiveness of tDCS to improve clinical interventions in SAUD. Results. We provide an integrative overview of studies applying tDCS in clinical populations with SAUD, together with a standardized methodological quality assessment. We show that the currently available data remain inconsistent. Some data suggested that tDCS can (1) reduce craving, relapse or alcohol-cue reactivity and (2) improve cognitive control and inhibition. However, other studies did not observe any beneficial effect of tDCS in SAUD. Conclusions. Capitalizing on the identified strengths and shortcomings of available results, we present evidence-based clinical guidelines to integrate tDCS in current clinical settings and to combine it with neurocognitive training.

Prefrontal cortex parvalbumin interneurons exhibit decreased excitability and potentiated synaptic strength after ethanol reward learning

The prefrontal cortex (PFC) is intimately associated with behavioral characteristics of alcohol use disorders, including high motivation to drink and difficulty with moderation. Thus, continued mechanistic research investigating PFC cells and targets altered by ethanol experiences should inform translational efforts to craft new, efficacious treatments. Inhibitory interneurons expressing parvalbumin (PV-INs) comprise only a minor fraction of cells within the PFC, yet these cells are indispensable for coordinating PFC ensemble function, oscillatory activity, and subcortical output. Based on this, PV-INs represent an exciting target for the rational design of breakthrough treatments for alcohol use disorders. Here, we assessed experience-dependent physiological adaptations via ethanol place conditioning. By manipulating the timing of administration relative to conditioning sessions, equivalent ethanol exposure can form either rewarding or aversive memories in different individuals. Here, we found that female mice and male mice on a C57BL/6J background display conditioned place preference (CPP) or aversion (CPA) to an intoxicating dose of ethanol (2 g/kg, intraperitoneal [i.p.]) without overt differences between sexes. Ethanol reward learning was associated with decreased PV-IN excitability in deep layer prelimbic PFC, whereas PV-INs from CPA mice were not different from controls. Furthermore, PV-INs from mice in the CPP group, but not the CPA group, displayed potentiated excitatory synaptic strength that emerged during 1 week of abstinence. Taken together, these findings illustrate that synaptic and intrinsic adaptations associated with ethanol can depend on an individual's experience. These studies provide further context and support for PFC PV-INs as intriguing targets for modulating alcohol associations.

Neurofilament Light Chain as a Biomarker for Monitoring the Efficacy of Transcranial Magnetic Stimulation on Alcohol Use Disorder

Objective

This study assessed the effects of repetitive transcranial magnetic stimulation (rTMS) of the left dorsolateral prefrontal cortex (DLPFC) on serum neurofilament light chain (NfL) levels, alcohol consumption, craving, and psychological impairment in participants with alcohol use disorder (AUD).

Methods

Participants with AUD were randomly assigned to receive one of two treatments (active or sham rTMS). All participants received 10 daily active or sham rTMS sessions over the left DLPFC for 2 weeks, with follow-up visits at baseline and immediately after the completion of the treatments. Serum samples were obtained before and after the intervention. Days of heavy drinking, visual analog scale (VAS) scores, and mental health component scores (MCSs) of the Medical Outcomes Study 36-Item Short Form Health Survey were used to assess the effects of rTMS.

Results

Active rTMS had a significant effect on reducing days of heavy drinking, alcohol craving, and serum NfL levels, and improved social functioning and mental health. The improvement with active rTMS was significantly greater than that with sham rTMS. Correlation analysis revealed that the reduction in the baseline drinking level was positively correlated with declines in the VAS and NfL levels but not with psychological scores.

Conclusion

Repetitive transcranial magnetic stimulation of the left DLPFC was associated with reducing alcohol consumption and craving in patients with AUD and positively impacted neuropsychological and social function. Serum NfL levels may be useful as an early serological indicator of alcohol-induced brain injury.

The effects of unilateral transcranial direct current stimulation on unimanual laparoscopic peg-transfer task

INTRODUCTION

Efficient training methods are required for laparoscopic surgical skills training to reduce the time needed for proficiency. Transcranial direct current stimulation (tDCS) is widely used to enhance motor skill acquisition and can be used to supplement the training of laparoscopic surgical skill acquisition. The aim of this study was to investigate the effect of anodal tDCS over the primary motor cortex (M1) on the performance of a unimanual variant of the laparoscopic peg-transfer task.

METHODS

Fifteen healthy subjects participated in this randomized, double-blinded crossover study involving an anodal tDCS and a sham tDCS intervention separated by 48 h. On each intervention day, subjects performed a unimanual variant of laparoscopic peg-transfer task in three sessions (baseline, tDCS, post-tDCS). The tDCS session consisted of 10 min of offline tDCS followed by 10 min of online tDCS. The scores based on the task completion time and the number of errors in each session were used as a primary outcome measure. A linear mixed-effects model was used for the analysis.

RESULTS

We found that the scores increased over sessions (p < 0.01). However, we found no effects of stimulation (anodal tDCS vs. sham tDCS) and no interaction of stimulation and sessions.

CONCLUSION

This study suggests that irrespective of the type of current stimulation (anodal and sham) over M1, there was an improvement in the performance of the unimanual peg-transfer task, implying that there was motor learning over time. The results would be useful in designing efficient training paradigms and further investigating the effects of tDCS on laparoscopic peg-transfer tasks.

Intermittent Theta Burst Stimulation in Veterans with Mild Alcohol Use Disorder

BACKGROUND

Alcohol use disorder (AUD) is highly comorbid with depression and posttraumatic stress disorder (PTSD) and can complicate their treatment. Transcranial magnetic stimulation is a promising treatment for these disorders, yet prior research often excluded AUD patients out of concern for safety or poorer outcomes. To this end, we revisited a prior study of intermittent theta burst stimulation (iTBS) for PTSD, to evaluate whether mild AUD impacted safety and clinical outcomes.

METHODS

Fifty veterans with PTSD (n=17, with comorbid AUD) received 10 days of sham-controlled iTBS, followed by 10 unblinded sessions. Stimulation was delivered at 80% of the motor threshold for 1800 pulses to the right dorsolateral prefrontal cortex. Safety, PTSD and depressive outcomes were evaluated with repeated measures analysis of variance, to examine the effects of time, treatment group and comorbid AUD.

RESULTS

iTBS was safe, although AUD patients reported more adverse events, regardless of whether they received active or sham stimulation. Regarding clinical outcomes, patients with AUD who received active stimulation demonstrated a greater rate of improvement in depression symptoms than those without comorbid AUD. The presence of AUD did not impact PTSD symptom change.

LIMITATIONS

Limitations include a modest sample size and use of a categorical, rather than continuous, index of AUD diagnosis.

CONCLUSION

While these results require replication, they indicate that iTBS is likely safe in patients with mild comorbid AUD. We propose that comorbid AUD should not preclude clinical use of iTBS, and that iTBS should be further investigated as a novel treatment option for AUD.

Deep Network Pharmacology: Targeting Glutamate Systems as Integrative Treatments for Jump-Starting Neural Networks and Recovery Trajectories

Significant advances in pharmacological treatments for mental illness and addiction will require abandoning old monoaminergic theories of psychiatric disorders and traditionally narrow approaches to how we conduct treatment research. Reframing our efforts with a view on integrative treatments that target core neural network function and plasticity may provide new approaches for lifting patients out of chronic psychiatric symptom sets and addiction. For example, we discuss new treatments that target brain glutamate systems at key transition points within longitudinal courses of care that integrate several treatment modalities. A reconsideration of what our novel and already available medications are intended to achieve and how and when we deliver them for patients with complex illness trajectories could be the key to unlocking new advances in general and addiction psychiatry.

Regionally specific gray matter volume is lower in alcohol use disorder: Implications for noninvasive brain stimulation treatment

BACKGROUND

There is growing interest in neuromodulation-based therapeutics as tools for individuals with alcohol use disorder (AUD). Through electromagnetic induction, techniques such as transcranial magnetic stimulation (TMS) can noninvasively depolarize cortical cells in the induced electrical field and monosynaptic afferents. The ability of TMS to modulate the brain is dependent upon two factors, which may be compromised in individuals with AUD: (1) gray matter volume (GMV) at the site of stimulation and (2) scalp-to-cortex (STC) distance. This study tested the hypotheses that these aspects of neural architecture are compromised in AUD patients, and thus AUD patients may need a higher TMS dose to depolarize the cortex.

METHODS

High-resolution magnetic resonance images were acquired from 44 individuals with AUD and 44 age-matched healthy controls (n = 88). Whole-brain voxel-based morphometry was conducted. Subsequent region-of-interest analysis was performed at three EEG 10-20 sites commonly used in TMS for AUD: FP1 (left frontal pole), F3 (left DLPFC), and C3 (left motor cortex). STC distance and TMS electric fields were assessed at these EEG sites.

RESULTS

Individuals with AUD had significantly lower GMV in the bilateral orbitofrontal cortices, supramarginal gyri, and the left DLPFC (voxel-threshold p < 0.05, cluster-threshold p < 0.05) and within all 3 TMS target locations, F (1, 264) = 14.12, p = 0.0002. There was no significant difference in STC distance between the AUD and the healthy control group at any tested cortical location, F (3, 252) = 1.906, p = 0.129.

CONCLUSIONS

Individuals with AUD had significantly lower GMV in multiple areas of interest for TMS treatment; however, these volumetric reductions did not impact STC distance. Given previous studies that have shown TMS-evoked changes in cortical and subcortical activity to be dependent on GMV, these data suggest that individuals with AUD may require higher doses of TMS to sufficiently modulate the neural circuits of interest.

Repetitive transcranial magnetic stimulation as a potential treatment approach for cannabis use disorder

The expanding legalization of cannabis across the United States is associated with increases in cannabis use, and accordingly, an increase in the number and severity of individuals with cannabis use disorder (CUD). The lack of FDA-approved pharmacotherapies and modest efficacy of psychotherapeutic interventions means that many of those who seek treatment for CUD relapse within the first few months. Consequently, there is a pressing need for innovative, evidence-based treatment development for CUD. Preliminary evidence suggests that repetitive transcranial magnetic stimulation (rTMS) may be a novel, non-invasive therapeutic neuromodulation tool for the treatment of a variety of substance use disorders (SUDs), including recently receiving FDA clearance (August 2020) for use as a smoking cessation aid in tobacco cigarette smokers. However, the potential of rTMS for CUD has not yet been reviewed. This paper provides a primer on therapeutic neuromodulation techniques for SUDs, with a particular focus on reviewing the current status of rTMS research in people who use cannabis. Lastly, future directions are proposed for rTMS treatment development in CUD, with suggestions for study design parameters and clinical endpoints based on current gold-standard practices for therapeutic neuromodulation research.

Sensory cue reactivity: Sensitization in alcohol use disorder and obesity

Neuroimaging techniques to measure the function of the human brain such as electroencephalography (EEG), positron emission tomography (PET), and functional magnetic resonance imaging (fMRI), are powerful tools for understanding the underlying neural circuitry associated with alcohol use disorder (AUD) and obesity. The sensory (visual, taste and smell) paradigms used in neuroimaging studies represent an ideal platform to investigate the connection between the different neural circuits subserving the reward/executive control systems in these disorders, which may offer a translational mechanism for novel intervention predictions. Thus, the current review provides an integrated summary of the recent neuroimaging studies that have applied cue-reactivity paradigms and neuromodulation strategies to explore underlying alterations in neural circuitry as well in treatment strategies in AUD and obesity. Finally, we discuss literature on mechanisms associated with increased alcohol sensitivity post-bariatric surgery (BS) which offers guidance for future research to use sensory percepts in elucidating the relation of reward signaling in AUD development post-BS.

The neural, behavioral, and epidemiological underpinnings of comorbid alcohol use disorder and post-traumatic stress disorder

Alcohol use disorder (AUD) and (PTSD) frequently co-occur and individuals suffering from this dual diagnosis often exhibit increased symptom severity and poorer treatment outcomes than those with only one of these diseases. Although there have been significant advances in our understanding of the neurobiological mechanisms underlying each of these disorders, the neural underpinnings of the comorbid condition remain poorly understood. This chapter summarizes recent epidemiological findings on comorbid AUD and PTSD, with a focus on vulnerable populations, the temporal relationship between these disorders, and the clinical consequences associated with the dual diagnosis. We then review animal models of the comorbid condition and emerging human and non-human animal research that is beginning to identify maladaptive neural changes common to both disorders, primarily involving functional changes in brain reward and stress networks. We end by proposing a neural framework, based on the emerging field of affective valence encoding, that may better explain the epidemiological and neural findings on AUD and PTSD.